Probably a dumb question here...but exactly how does one know how much setback they need (or don't need, if that is the case)? I've had many fittings (include Retul), but the fitter never mentioned "setback" to me, so I have no clue. FWIW, the seat post on my Cannondale Synapse is one of those teardrop-shaped aero posts, so it's not like I can easily swap it out for something with more (or less) setback. Infact, I really dislike the entire seatpost/clamping system on the Synapse because small adjustments are virtually impossible to make.